The CC-101 Closed Caption Decoder/Text Video Overlay captures the closed captioning text (CC1 to CC4), information and it then overlays it on the video output. It achieves this with an option to stream to the serial port.

The CC-101 Closed Caption Decoder/Text Video Overlay captures
the closed captioning text (CC1 to CC4), information and it
then overlays it on the video output. It achieves this with
an option to stream to the serial port. The Decoder includes
a serial port, through which it can display user-defined text
anyplace on the screen. The device includes EEPROM (internal
non-volatile flash memory) which enables you to store up to
ten (10) strings of data and auto-display them either when
you turn on the system or activate the playback through the
front panel. It implements Free Windows™ software that allows
you to define and store text in the CC-101's memory for
playback.